Frame supported resistor grids such as the article of U.S. Pat. No. 4,100,526 are widely used in diesel electric locomotives. The heat generated by such resistors in their braking function and the vibration inherent in any railroad vehicle creates problems not easily solved. The units generally comprise one or more fan-folded strips of resistance material arranged in columns supported by insulators in a grounded metal frame. The insulators mounted in the frame hold the strip in position by metal studs affixed to each fold of the strip, which studs are received in the insulators. The studs are generally welded to the strip of resistance material. The insulators, which are often ceramic, but may be of other non-conductive material, are affixed to the frame in various ways. In FIG. 2 of U.S. Pat. No. 4,100,526 an E ring is shown as the device for anchoring a cylindrical ceramic insulator in a metal frame.
While the prior art devices for mounting ceramic insulators in metal frames are reasonably satisfactory, the insulators can be loosened by vibration. E rings and similar frictional devices must have spring-like projections to withstand the vibration of railroad cars. Steel springs are made from spring steel which has a carbon content of about 1%. It cannot be welded because the heat of the weld would "draw" its temper, that is, destroy its springiness.